Modify Settings on an AR636 SAFE Select Receiver

In 2016, Horizon/Spektrum introduced "SAFE Select", a new variation of their beginner-oriented SAFE stabilization system. SAFE Select is based on the AR636 receiver, which has proven to be very versatile for a number of applications based on the way it's programmed by HH.

A feature that was new with SAFE Select is the ability to adjust at least some of the settings in the AR636 using the Spektrum Programmer software (SPS). Prior to SAFE Select, the programming on SAFE receivers was completely locked out despite the fact that the AR636 is normally programmable from a phone app or the PC software.

The information in this thread has evolved quite a bit since it was first opened in June 2017. Although Spektrum still hasn't provided all of the tools to fully configure the SAFE features on an AR636 receiver, I've brought a lot of information together and developed a programming tool for SAFE with an AR636.

The information in post # 2 is an "old" way of manually changing the SAFE settings inside a text file that comes from SPS. That has been replaced with the program in post # 4.

Post # 5 contains some model setup files (SRM files) that provide a good starting point for configuring your own SAFE model.

If you have never installed a receiver with SAFE in another airplane, or you're new to SAFE, I encourage you to check out the Ultimate Guide to Installing an AR636 with SAFE in post # 6. It's a combination of the documents in posts # 3 and # 4, along with some information from the process of installing an Apprentice S SAFE receiver in another plane. It explains how SAFE works, and it also explains one of the most important aspects of this process - how to test your airplane on the ground to make sure the receiver is working correctly.

This first post talks about some of the basic things you can - and cannot - modify using SPS alone. This was step one in the process of learning how to work with SAFE Select receivers.

Not all of the settings in the Spektrum Programmer software apply to SAFE Select programs. Also, SPS does not have screens to modify the SAFE features (self-level, panic, etc.) There are two key areas of most interest if you want to install a SAFE Select receiver in another airplane - the Mounting Orientation and the Control Surface Setup. Because the receiver needs to move the control surfaces in the correct direction, those are very important settings on the receiver! The Surface Setup can be changed on SAFE Select receivers, but the Mounting Orientation cannot be changed using SPS.

The Basics of Using SPS
This document is a basic walkthrough for how to get the Spektrum Programmer software running on a PC, connect a receiver, and make changes on the SAFE Select receivers. It's not an exhaustive explanation of all of the various settings available. Spektrum made an excellent series of videos when the AR636 first came out, and even though they use the phone app instead of the PC software in the videos, all of the explanations apply the same way. Their YouTube playlist is here:https://www.youtube.com/playlist?lis...RshoLuMZKu_Gi1

At the time of this writing, only the PC software recognizes SAFE Select receivers; the phone app does not.

Changing the SAFE Features SPS Cannot Change
See the next post (# 2) for how to change the Mounting Orientation and the settings directly related to SAFE features.

Modify SAFE Settings

In October 2017, there was a revelation in the "E-Flite SAFE RX In Another Plane Thread"! It was discovered that you could edit a lot more settings inside the AR636 configuration for a SAFE Select receiver if you went above and beyond the capabilities of the Spektrum Programmer Software (SPS).

In a nutshell, this is the process for making those changes:

1. Have the SPS read the settings in your receiver.
2. Export those settings to an SRM file, which is a text file.
3. Use a text file editor to read the file, type in strategic changes, and save the file.OR, use my SAFE Model Builder program to help you make those changes and save the file.
4. Import that SRM file back into SPS.
5. Have SPS load the changes into the receiver.

The document in this post is a walkthrough for how to edit settings for SAFE features by editing the text file directly.

To use my SAFE Model Builder program, see post # 4 below.

If you are not at all familar with the SPS software, then I'd suggest you start with the walkthrough in the above post first, even if you don't want to make any changes that way. It will help you get the SPS software installed and get your receiver connected for the first time.

VERSION 3
Corrects an error about a method of disabling the bank angle limits. Previous versions stated that you can do that by setting the angle to 0; that's not accurate. Instead, that's only done through the "feature" setting mentioned in section 2.4 of the document.

DISCLAIMER: Personally, I haven't flown a plane after making the modifications using the process described in this document. I have bench tested on the ground as thoroughly as I can, and I have gone through the process many times already. Also, this is outside the bounds of Horizon Hobby support. If you try to edit settings this way and something bad happens to your receiver, don't expect HH to take any responsibility for it.

This new version has several new features, the biggest of which is the ability to apply version 2.xx of the firmware, which will allow you to get SAFE capabilities on an AR636 or AR636A* receiver that didn't originally come that way. Other features include the ability to power the receiver through the USB programming cable (instead of using a BEC or the aircraft's power system), and the ability to connect to the Spektrum Web site for you to find and apply firmware updates.

* Horizon Hobby does not officially support upgrading AR636A's using this process. It's only meant for open stock AR636's.

This document explains how to upgrade the firmware and then load a new model setup (or "SRM file") to give the receiver new capabilities.

One note - I have changed the order of the way things are done to connect the receiver to the computer. The other documents above mention starting the Spekrtum Programmer Software first, and then plugging in the USB cable. But in the video that Spektrum put out with version 3.2 of SPS, they tell you to plug in the USB cable first and then start SPS. While it seems to work fine either way, I changed my process to match Spektrum's.

VERSION 3 UPDATE - Added a little more info about the calibration process, and also a note about being mindful of the mounting orientation when you apply settings from a different model.

VERSION 2 UPDATE - Streamlined the process of applying a new SRM file to the receiver - it's not necessary to disconnect the receiver before selecting another model. Also changed the process for applying power to the receiver using the USB cable; it's now more consistent with applying power from a BEC or ESC.

Files

SAFE Model Builder Program

As mentioned in the earlier posts in this thread, it was discovered that you could edit a lot more settings inside the AR636 configuration for a SAFE Select receiver if you went above and beyond the capabilities of the Spektrum Programmer Software (SPS).

In a nutshell, this is the process for making those changes:

1. Have the SPS read the settings in your receiver.
2. Export those settings to an SRM file, which is a text file.
3. Use a text file editor to read the file, type in strategic changes, and save the file.OR, use my SAFE Model Builder program to help you make those changes and save the file.
4. Import that SRM file back into SPS.
5. Have SPS load the changes into the receiver.

For a much more comprehensive document about the entire process of installing an AR636 with SAFE in another airplane (including testing on the ground first), see post # 6 of this thread.

It's August 2018, and Spektrum still hasn't updated the SPS software to include changing the SAFE features. Even worse, it still has the Mounting Orientation screen disabled. So even if you just want to move a SAFE-enabled AR636 receiver to another airplane as it is, you can't program the Mounting Orientation for the new plane.

To make it easier to change SAFE settings, I have written a basic program that gives you a point-and-click way to change the SAFE settings outside of SPS.

If you are not at all familar with the SPS software, then I'd suggest you start with the walkthrough post # 1 of this thread, even if you don't want to make any changes that way. It will help you get the SPS software installed and get your receiver connected for the first time.

To use this program, simply unzip the contents of the ZIP file below. You must keep the EXE file together with the Netwonsoft DLL file in the same folder. You just run the EXE file to run the program - there is nothing to install. I have also included a variety of sample SRM files, most of which are Spektrum model setups that have been exported from SPS unchanged. Those files give you a starting point for setting up a receiver for a different plane. For example, to see a setup with the traditional three-mode SAFE similar to the Apprentice S, look at the Mini Apprentice file.

The EXE file is not digitally signed, so your anti-virus software will question it the first time you run it. I'm very paranoid about security myself, so I understand you're taking a leap of faith using it. It's not a virus, and it doesn't work with any data it's not supposed to. It's written with Visual Studio for .NET 4.0. I don't know what .NET does by default for any program Visual Studio creates, but my code doesn't access the registry, the network, or any files you don't tell it to open or save.
As I created it, here's the SHA-1 Checksum for the ZIP File (version 1.6.1): 842a06fae2e19207fdc970262765a2c9b7b3edf1

Full documentation with screen shots is provided in the PDF file below.

Many thanks go to the contributors in the "Experimenting with SAFE Settings" thread here, especially those who have been helping test the program and provide feedback to improve it since it was first released in post # 532.https://www.rcgroups.com/forums/show...tings-on-AR636

DISCLAIMER: This program, and even this whole process of editing model files exported from SPS, is not supported by Horizon Hobby. Use this at your own risk, and thoroughly test the way the receiver is working in your plane on the ground before you fly it.

UPDATE - Version 1.1 - September 26, 2018
- Added a check that will warn you if you save a model that has some SAFE features selected on the Flight Modes tab, but SAFE is not enabled overall on the Switch Setup tab
- Corrected a spelling error on the THR>ELE mix tab
- Changed some wording on the Switch Setup tab

UPDATE - Version 1.2 - October 14, 2018
- Cleaned up the tab order, so pressing the Tab key to move around the screen does so in a much more logical manner.
- Added the Modified Mini Apprentice model setup (SRM) file inside the ZIP file. See post #5 below for details about that setup.

UPDATE - Version 1.3 - November 30, 2018
- Added a setting on the Advanced tab for changing the receiver firmware version for which the model file is intended. (That's the "parameterVersion" setting inside the SRM file.) This is a very advanced feature, intended to work around some artificial limitations in the Spektrum Programmer Software when working with SAFE-enabled models (firmware version 2.xx).

UPDATE - Version 1.4 - December 1, 2018
- The program will no longer allow you to enable the THR>ELE mix feature in a given flight mode if the Self-Level feature is not also enabled. THR>ELE mix doesn't work properly if self-level is not enabled!

UPDATE - Version 1.5 - July 4, 2019 (826 downloads!)
- Added support for the ELFU5864 combination ESC/receiver ("brick") for the UMX Cessna. The EFLU5864 is essentially a miniature AR636 and can be programmed as such!
- Added support for selecting whether or not the heading gains are absolute (set according to how you program the receiver) or relative (can be changed from a Spektrum transmitter with an LCD screen and telemetry).

UPDATE - Version 1.6 - April 12, 2020 (37 downloads)
- Fixed the issue where the SAFE features on Horizon Hobby BNF model setups were not being displayed accurately. This includes both Bank Angle Limit (Envelope) and THR>ELE mix showing as off when they're really active.
- Whenever the Self-Level / Angle Demand feature is active for a flight mode, SMB will now turn on Bank Angle Limits (Envelope) automatically and force it to stay on. This is a more accurate representation of what's happening in the receiver, because Self-Level / Angle Demand doesn't work with bank angle limits.
- Added the terms "Angle Demand" and "Envelope" to the Flight Modes tab for consistency with the AR637T terminology.
- The display of the feature code on the Flight Modes tab is now hidden. For most people, that was really just a distraction anyway; it's only helpful if you are trying to read the settings in the SRM file with a text editor. If you'd like to see the feature codes, click the underscore ("_") in the lower right corner of the Flight Modes tab.

UPDATE - Version 1.6.1 - April 16, 2020
- Changed the wording for the description of Attitude Trim values. Turns out that it was incorrect (or at least very confusing) for a long time!

Custom Mini Apprentice and Apprentice S SRM Files

Here are a couple of models you can use as a starting point for putting SAFE in another plane.

Both are based on Spektrum's Mini Apprentice setup. I chose that one because of all the success we had putting the Apprentice S receiver in a number of other airplanes. Even though the Apprentice S receiver is not programmable, the gain settings that were built-in seemed to work fine for all but the most aerobatic styles of planes. I'm assuming the same is true with the Mini Apprentice, as it's still a high-wing trainer and just slightly smaller than the Apprentice S. Also, this setup is designed for three flight modes, rather than having the SAFE Select configuration with the appearance of only two modes - SAFE On and Off.

To create this SRM file, here's what I did:
1. Loaded the Spektrum Mini Apprentice file into SAFE Model Builder.
2. Changed the model name.
3. Changed the mounting orientation to pins toward tail, label toward sky (a lot more typical than the Mini Apprentice's setting on its edge).
4. Saved the SRM file.
5. Imported the SRM file into Spektrum Programmer Software.
6. Removed all Expo - all set to 0% in all flight modes for all controls.
7. Set Dual Rate to 100% in all flight modes for all controls.
8. Deleted the AIL > RUD (roll > yaw) mix that HH added to this particular plane.
9. Exported the SRM file.

These changes give it a more "vanilla" configuration, with no mysterious changes to your control inputs with the exception of the standard SAFE THR>ELE mix.

From there, I took that Custom Mini Apprentice file and modified it a little more so that it's close to being a drop-in replacement for an Apprentice S receiver.
- Changed the bank angle limits to be closer to those observed on a plane equipped with the Apprentice S. Set the pitch to 40 (both directions) and roll to 50 (both directions) in mode 1 (Beginner Mode), and set the pitch to 45 up / 40 down and roll to 65 (both directions) in mode 2 (Intermediate Mode).
- Changed the direction of the panic button so that it matches the transmitter setup for the real Apprentice S.
- Changed the THR>ELE mix so that it's much closer to the Apprentice S straight 20% mix. Set it for 0 elevator input on the low side (below 20), and -15 elevator input on the high side (above 21). Also set it to proportional, not constant value.
- Changed the direction of the rudder control in SPS so that the control directions match those of the Apprentice S receiver. For an AR636 to match the control directions of the Apprentice S, the rudder should be "normal", the elevator should be "normal", and the ailerons should be "reverse" in SPS.

One key difference between this Apprentice S setup and the real Apprentice S receiver is that I did not apply any low rates in the model setup. You can choose to apply low rates in either the receiver or your transmitter if you choose to. Here are the rates that you would set up:
Aileron and Elevator: 80% in mode 1 (Beginner Mode), 100% in other flight modes
Rudder: 50% in mode 1 (Beginner), 60% in mode 2 (Intermediate), and 70% in mode 3 (Experienced)
When you transplant the Apprentice S receiver to another plane, these low rates often result in reduced control authority.

Of course you can make more changes to your liking. You can change all of the SAFE features using the SAFE Model Builder, and you can change other settings in SPS.

Ultimate Guide to Installing AR636 with SAFE

This document is a combination of several other pieces of documentation I've written over time.

If you have never installed a receiver with SAFE in another airplane, or you're new to working with programming the SAFE features, then this guide is for you!

It's broken into seven sections. You can read or skip any sections as you choose:
Section 1 – What is SAFE?
Section 2 – Installing and Using Spektrum Programmer Software (SPS)
Section 3 – Checking and Upgrading the Receiver Firmware
Section 4 – Creating a Model Setup for the AR636 with SAFE
Section 5 – Apply Model to Receiver and More using SPS
Section 6 – Creating a Model on Your Transmitter
Section 7 – Testing the Controls

A lot of this information is included in the documents in the other posts in this thread, but now it's all in one place. Section 1 is brand new, explaining a little of the history of SAFE and what features are part of the "SAFE" system. Section 6 provides some pointers to more info elsewhere in my blog about transmitter setups. Finally, Section 7 is from one of my previous documents about installing an Apprentice S SAFE receiver in another plane, but it's just as important to go through those tests on the ground with an AR636 receiver as well.

Revision 2 - February 8, 2019
Fixed some information that was missing on page 36. It was a cut-and-paste error I made taking some text from one of my other documents.